Pyrographic pencil



Dec. 14, 1937. E L MEYER 2,101,913

PYROGRAPHIC PENCIL Filed Jan. l5, 1936 Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE 6 Claims.

This inventionk relates to electric pyrographic pencils.

An object of this invention is to provide a pencil of this kind in which the temperature of the part applied to the work may be varied at the will of the user.

Another object is to provide a pencil in which the part applied to the Work may be varied in shape to suit the users needs, and, preferably,

may be formed into designs which are repeatedly used in the work being executed.

A still further object is to provide an electric pyrographic pencil which may be used with currents of very low voltage so that danger of the user being shocked upon inadvertently touching the terminals is eliminated. This is accomplished by utilizing a heating resistance which is brought directly in contact with the Work, and, therefore, may be very short so that it may be brought to desired temperature by currents of extremely low potentialsl volt or less if desired.

Other features and advantages will hereinafter appear.

In the accompanying drawing which shows the present invention in its preferred form- Figure l is a perspective view of the device of the present invention, showing the manner in which the pencil may be used.

Fig. 2 is an elevation showing the rear end of the holder broken away to show the manner in which the current-conducting wires are connected to the conducting members.

Fig; 3 is a longitudinal sectional view of the working end of the pencil.

35, Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig, 3.

Fig. 5 is a transverse sectional view taken on the line 5 5 of Fig. 3.

Fig. 6 is a longitudinal section of the operating end of the current-conducting bars showing the loop of the resistance Wire as extended far beyond the ends of the conducting members.

Fig; 7 is a similar view, showing the loop of the resistance wire located closely adjacent to the ends of the conducting members.

Fig. 8 is a perspective view of one of the clamping screws by means of which the ends of the resistance Wire are secured to the conducting members.

Figs. 9, l0, ll and l2 are views in perspective showing, respectively, various forms in which the resistance wire may be bent-the Wires shown constituting burning elements which may be interchangeably secured in the holding device f shown in Figs. 1 and'2.

(Cl. 21S-29) As shown in the accompanying drawing, the deviceV of thepresent invention comprises a handle portion I0 which may be made of Wood, cork, or the like. The handle portion I0 is tubular and its longitudinally extending hole is preferably 5l beyond the handle portion Ill and the heat in- 10` sulating material II.

In the form of the invention at present preferred, the current-conducting members I2 and I3 preferably snugly t within the lining I I in the handle portion I0, and, since the passage 15 through the handle portion is cylindrical, the conducting bars are preferably made semicylindrical, i. e. half round, or substantially so. T'hey are separated electrically by a strip of insulating material I5 extending longitudinally be- 20 tween the half-round conducting bars I2 and I3, and the latter with the insulating strip I5, preferably completely lls the longitudinal passage in the handle portion I0.

If desired, the conducting bars I2 and I3 may 25 be held in the handle portion positively against relative movement by screws I 6. The conducting members I2 and I3 extend for practically the entire length of the handle, but, at the end thereof, which is opposite the projecting ends I4, the 30 handle portion I0 extends beyond the conducting members I2 and I3 and forms a socket for the reception of a plug I1 of insulating material having within it contact members I8 connected to wires I9 by means of which current is supplied 35 to the device, the plug having a cap 20 which limits the movement of the plug into the top end of the handle.

The conducting members I2 and I 3 are provided with blades 2| engaging the contacts I 8, 40 I B of the plug. Thus, when the plug is connected to the handle, the current is conducted through the conducting bars I2 and I3.

Instead of employing, as was heretofore customary, an electrical resistance to heat a burning 45 point on the pencil, the present invention makes provision for bringing an incandescent resistance Wire directly in contact with the work. By so doing, the heat generated by the heating element, being exterior of the handle, does not excessively 50 heat the handle portion and less heat need be developed since it is applied directly, and currents of such low potential as to be harmless to the operator may be employed.

According to the present invention, the heat- 55 ing element comprises a strand of resistance wire 22 which may, as shown in Figs. l and 2, have a loop portion 23 and tine-like end portions 2d adapted to be inserted in the end of the pencil. In the form shown, the ends 26 of the wire are inserted in sockets provided in the ends ifi of the conducting members I2 and I3, and, to receive the wire, the conducting members I2 and I3 are provided withrlongitudinally extending grooves 25, preferably V-shape. 1

The insulating strip I5 being located between the grooved portions of the conducting bars I2 and I3 forms in each of the latter a socket to x receive the tines of the resistance wire.

In the broader aspects of YthisY invention, the resistance wire may be held in the sockets in any suitable or desirable way. It isA preferable, how-Y ever, that the wire ends be mounted for longitudinal movement within the sockets so that a greater portion of the legs 24 may extend lbeyond the current-conducting members I2 and I3 as shown in Figf, or a'lesser portion as shown in Fig.' '7. In this'way,the degree of incandescence or the temperature to which the burning wire may beV brought when energized may be varied,

for, in moving the wire into and out of the sockets,

less orv more o1 the wire is made electrically effective, and, therefore, the temperature of the a'threaded stud or screw l'having at its lower 2d of the burning wire are inserted in the sockets 25, the ends thereof pass through the apertures l'when the'nut 2S is loosened. When, however,

thenut is tightened, the naked portion of the wire is drawn outwardly securely clamping it to the end Il of the conducting bar. To increase the binding action between the clamping stud 2l and the wire, a deeper groove S'is provided inV the end Ifi Vof the conducting member so that when the screw is drawn outwardly, a bend 3i will be formed in the wire end, and this bend will resist longitudinal movement -of the tines 24 until the screw is again released. Y

The enlarged groove is preferably also` V- shape, and the inner'end of the screw 2I is provided with a head 32 lying in this V-shapedV groove.

The head 32 has flat sides which, engaging the walls of' the V-shaped groove Se, causes Athe stud 2l" to be so positioned that the aperture 28 will beV in alignment with the V- shaped grooves 25 receiving the wire ends, so that the tines 2li may easily and conveniently pass throughthe holes 28 in the clamping screws.

`The grooves 25 in the members I2 and I 3 may extendY for substantially the entire length of the bars I2 and I3, so that great excessof wire may be stored inthe handle portion out of the way and to be used more or less depending upon the will of the operator.

The resistance wire of which the burning element 22 is formed is preferably sumciently ductile to permit the user to shape the loop portion into various designs so that these designs may be,

The screw2'I extends through a' as in branding, reproduced at various places on the work. For instance, as shown in Fig.V 9, the burning element 22a has a diamond-shape loop portion 23a, while the burning element 22h of Fig. 10 has a'circular loop portion 23h, and the stantially perpendicular to the work, the design outlined by the loop portion will be produced on the work asby branding. The burning element 22d= shown in Fig. l2 is also provided with a be placed at once on the 'working surface. Y

It should be noted that, according to the present invention, the loop of the burning wire 22 is spaced substantially from the handle and conducting members I2 andV I3, and that it is free and is unsupported except by the ends of the wires in which the loop forms apart. Being free and unsupported, heat developed by the wire is not readily conducted to the handle, and the wire, although stii enough to sustain the'shape given it by the user, may be formedinto desired shapes Vor forms.

As shown in Fig. l, the handle portion I is` gripped by the fingers ofthe operators hand and employed like a penciLcausing the loop portion' 23 toY travel over the workV S3 which may be of Wood, leather, or other burnable material.

By employing a resistance wire as the means to be directly appliedV to the work, it is practical to energize the device with low potential currents of one volt for instance, or even less. This potential is suicient to raise the wire which will maintain its given shape when brought to incandescence, and to maintain it so as it continues to be applied to the work, These currents may be supplied from a suitable transformer connected to house current, if desired. While one of the main reasons for providing low voltage is: to avoid the dangers of the user being shocked, yet, by employing the'low voltage, a burning wire of satisfactory length, diameter and material may be used.

Variations and modifications may be made within the scope of this invention and portions of theY improvements may be used without others.

I claim:

l. Inan'electric pyrographic pencil, a handle having a longitudinally extending hole therein; aheat-resisting member lining the hole in said member; a' pair of low resistance conductors lying in parallel relation and together substantially fitting the hole within the heat-resisting member; current-insulating means interposed between said conductors and with the latter substantially illing said hole in the handle portion; and sockets in the ends of said conducting memsubstantially half-round bars tting a substantially cylindrical hole in the handle portion, and

each of the at sides of said metal bars beingV provided with a groove forming a channel for receiving one'end of the resistance wire.

2. In an electric pyrographic pencil, a handle having a longitudinally extending hole therein; a heat-resisting member lining the hole in said member; a pair of low resistance conductors lying in parallel relation and together substantially fitting the hole Within the heat-resisting meniber; current-insulating inea-ns interposed between said conductors and with the latter substantially filling said hole in the handle portion; and sockets in the ends of said conducting ineinbers at one end of the handle to receive and hold a Wire so to pass current therethrough, the conducting members being in the fori-n of substantially half-round bars fitting a substan tially cylindrical hole in the handle portion, and each of the flat sides of said metal bar being provided With a groove forming a channel for receiving one end of the resistance wire, said metal bars having clamps for securing the ends of the resistance wire in said grooves and said clamps being located adjacent the ends of the metal bars carrying the resistance Wire.

3. In an electric pyrographic pencil, a handle portion having a longitudinally extending hole therein; a pair of low resistance conductors arranged in said hole in side by side relation, each of said conductors having a substantially plane portion, said portions being substantially parallel and facing each other near the working end of the pencil; current-insulating means interposed between said conductors and engaging the snostantially plane portions thereof, said portions being grooved along the length of the pencil to form channels for receiving the end lengths of a resistance Wire; and a draft means passing through one of said plane portions and operable .from the exterior of the pencil to draw the associated end length of resistance Wire outward from the center line of the pencil to elaine said end length in said channel.

4. In an electric pyrographic pencil, a handle portion having a longitudinailf,T extending hole therein; a pair of low resistance conductors arranged in said hole in sideby side relation, each of said conductors having a substantially plane portion, said portions being substantially parallel and facing each other near the wor: end of the pencil; current-insulating means interposed between said conductors and engaging the substantially plane portions thereof, said portions being grooved along the length of the pencil to form channels for receiving the end lengths of a resistance Wire; and a draft means passing through one of said plane portions and operable from the exterior of the pencil to force the associated end length of the resistance Wire into said channel, said channel being locally deepened t cause said end length to be warped Where engaged by the draft means.

5. In an electric pyrographic pencil, a handle portion having a longitudinally extending hole therein; a pair of loW resistance conductors arranged in said hole in side by side relation, each of said conductors having a substantially plane portion, said portions being substantially parallel and facing each other near the Working end of the pencil; current-insulating means interposed between said conductors and engaging the substantially plane portions thereof, said portions being grooved along the length of the pencil to form channels for receiving the end lengths of a resistance wire; and a draft means passing through one of said plane portions and operable from the exterior of the pencil to force the associated end length of the resistance Wire inte said channel, said draft means including a threaded member crossing said channel and having an aperture for taking said end length.

6. In an electric pyrographic pencil, a handle portion having a longitudinally extending hole therein; a pair of low resistance conductors arranged in said hole in side by side relation, each of said conductors having a substantially plane portion, said portions being substantially parallel and facing each other near the Working end of the pencil; current-insulating means interposed betvveen said conductors and engaging the substantially plane portions thereof, said portions being grooved along the length of the pencil to form channels for receiving the end lengths of a resistance Wire; and a draft means passing through one of said plane portions and operable from the exterior of the pencil to force the associated end length of the resistance wire into said channel, said draft means including a threaded member crossing said channel and having an aperture for taking said end length, means being provided for holding said aperture aligned with the channel.

EDWIN L. MEYER. 

